Resin composition, resin varnish, prepreg, metal-clad laminated board and printed wiring board

ABSTRACT

The present invention relates to a resin composition that becomes a cured product that exhibits force response behavior such that an area surrounded by a tensile stress-strain curve f1(x), when an amount of strain is increased from 0% to 0.3% by pulling at 999 μm/min while plotting the amount of strain on the x axis and tensile stress on the y axis, and also surrounded by the x axis, is greater than an area surrounded by a stress-strain curve f2(x), when the amount of strain is decreased from 0.3%, and also surrounded by the x axis, and the amount of change in the amount of strain when tensile stress is 0, before and after applying tensile stress, is 0.05% or less.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Applications No.2013-160215 filed Aug. 1, 2013 and No. 2013-219022 filed Oct. 22, 2013,which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a resin composition, a resin varnish, aprepreg, a metal-clad laminated board and a printed wiring board.

BACKGROUND OF THE INVENTION

Accompanying the reduced size and thickness of electronic devices,surface mount packages are being increasingly used for electroniccomponents provided in these electronic devices. Examples of suchpackages include packages in which a semiconductor chip is mounted on aboard such as a chip-on-board (BOC) package. These packages employ astructure in which the semiconductor chip and board are bonded.Consequently, warpage and other forms of package deformation occurreddue to temperature changes attributable to a difference in thecoefficient of thermal expansion (CTE) between the semiconductor chipand the board. In addition, as this warpage increases, force that actsto separate the semiconductor chip and board becomes large, therebycausing a decrease in connection reliability between the semiconductorchip and board in these packages.

In addition, electronic devices are being required to become evensmaller and thinner. In order to satisfy these demands, efforts arebeing made to reduce the size and thickness of electronic components,and studies are being conducted to reduce the thickness of the boardsthat compose the packages of electronic components. In the case of aboard that has been reduced in thickness in this manner, there tends tobe increased susceptibility to the occurrence of warpage, therebyrequiring these boards to more effectively inhibit the occurrence ofwarpage.

Moreover, in order to make electronic devices multifunctional, it isnecessary to increase the number of electronic components installedtherein. In order to satisfy this requirement, a type of package knownas a Package on Package (PoP) is employed in which a plurality ofsub-packages are laminated and mounted on a board followed byintegrating into a single package. For example, these PoP are frequentlyemployed in portable terminal devices such as Smartphones or tabletcomputers. In addition, since these PoP are of a form in which aplurality of sub-packages are laminated, the connection reliability ofeach sub-package becomes important. In order to enhance this connectionreliability, it is necessary to reduce warpage of each package that isused as a sub-package.

On the basis thereof, studies have been conducted on the development ofboard materials that enable the production of boards that are able toadequately inhibit warpage even in the case of packages using boards ofreduced thickness. An example of these board materials is the resincomposition described in WO 2012/099134.

WO 2012/099134 describes a resin composition containing a maleimidecompound having at least two N-substituted maleimido groups in thestructure of a single molecule thereof and a silicone compound having atleast one amino group in the structure of a single molecule thereof.

According to WO 2012/099134, it is disclosed to the effect that amultilayer printed wiring board can be produced that has superior glasstransition temperature, coefficient of thermal expansion, soldering heatresistance and warpage characteristics, and is useful as a printedwiring board for electronic devices.

However, when using a board obtained using the resin compositiondescribed in WO 2012/099134, there are cases in which a package isunable to be obtained that adequately inhibits warpage and otherdeformation that occurs due to changes in temperature.

In this manner, a bonded body obtained by bonding two or more membersmade of different materials is subjected to stress in the direction inwhich warpage occurs caused by a change in temperature that is due to adifference in the coefficient of thermal expansion of each member.Consequently, in the case of a bonded body in which two or members madeof different material are bonded, the problem of the occurrence ofwarpage caused by a change in temperature may occur in the same manneras in the case of the packages described above. In addition, the problemmay also occur in which the bonded state of two members may be unable tobe maintained. It is therefore necessary to inhibit the occurrence ofsuch problems.

With the foregoing in view, an object of the present invention is toprovide a resin composition that allows the obtaining of a compact thatadequately inhibits the occurrence of warpage even in the case ofbonding to another member. In addition, an object of the presentinvention is to provide a resin varnish, a prepreg, a metal-cladlaminated board and a printed wiring board that use this resincomposition.

SUMMARY OF THE INVENTION

A resin composition according to one aspect of the present invention issuch that a cured product obtained by curing this resin compositionexhibits force response behavior in which an area surrounded by thefollowing tensile stress-strain curve f1(x) and the x axis is greaterthan an area surrounded by the following tensile stress-strain curvef2(x) and the x axis. Furthermore, the tensile stress-strain curve f1(x)described here has the amount of strain plotted on the x axis, tensilestress plotted on the y axis, and is a tensile stress-strain curve whenthe amount of strain by pulling at 999 μm/min is increased from 0% to0.3%. Moreover, the tensile stress-strain curve f2(x) is a tensilestrain-strain curve when the amount of strain is decreased from 0.3%. Inaddition, the cured product exhibits force response behavior such thatthe amount of change in the amount of strain when tensile stress is 0before and after applying tensile stress is 0.05% or less.

In addition, a resin varnish according to another aspect of the presentinvention contains the resin composition and a solvent.

In addition, a prepreg according to another aspect of the presentinvention is obtained by impregnating a fibrous base material with theresin varnish.

In addition, a metal-clad laminated board according to another aspect ofthe present invention is obtained by laminating a metal foil on theprepreg, followed by hot press molding.

In addition, a printed wiring board according to another aspect of thepresent invention is produced by using the prepreg.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram showing a type of force response behaviorof a resin composition according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

According to studies conducted by the inventors of the presentinvention, materials proposed as board materials for reducing packagewarpage, including the resin composition described in WO 2012/099134,were developed for the purpose of enhancing modulus of elasticity andlowering coefficient of thermal expansion. As a result of enhancingmodulus of elasticity, the rigidity of the board per se increases, theboard becomes resistant to bending, and the occurrence of warpage isthought to be able to be inhibited. In addition, if the coefficient ofthermal expansion is lowered, the difference in coefficient of thermalexpansion with a semiconductor chip becomes small, and force that actsto bend the substrate is thought to become weak.

However, even if using a board material developed for the purposesdescribed above, there were cases in which a package was unable to beobtained that adequately inhibited warpage and other deformationoccurring due to a change in temperature as previously described. Inaddition, even if the occurrence of warpage was able to be adequatelyinhibited, the range of materials that can be selected for that boardmaterial was narrow, and heat resistance and other requirements wereunable to be adequately satisfied.

Therefore, as a result of focusing on inhibiting the occurrence ofwarpage by intentionally lowering modulus of elasticity and causingdeformation of the board per se, and further conducting extensivestudies on conditions that enable the occurrence of warpage to beadequately inhibited, the inventors of the present invention defined arelationship according to a tensile stress-strain curve, thereby leadingto completion of the present invention as indicated below.

Although the following provides an explanation of embodiments accordingto the present invention, the present invention is not limited thereto.

The resin composition according to the present embodiment is such that acured product obtained by curing this resin composition exhibits forceresponse behavior like that described below. More specifically, anexample thereof is a resin composition that allows the obtaining of acured product that exhibits behavior like that shown in FIG. 1.Furthermore, FIG. 1 is a schematic diagram (graph) showing a type offorce response behavior of the resin composition according to thepresent embodiment. At that time, tensile stress is plotted on thevertical axis (y axis) while the amount of strain is plotted on thehorizontal axis (x axis).

In addition, FIG. 1 indicates the force response behavior of the resincomposition according to the present embodiment in which a tensilestress-strain curve f1(x), when the amount of strain has been increasedfrom 0% to 0.3% by pulling at 999 μm/min, is represented by a curve 11,and a tensile stress-strain curve f2(x), when the amount of strain hasbeen decreased from 0.3%, is represented by a curve 12. In addition,this graph indicates not only the force response behavior of the resincomposition according to the present embodiment, but also that for anelastic deformation resin, plastic deformation and the like.Furthermore, in FIG. 1, the force response behavior of a plasticdeformation resin is indicated by representing a tensile stress-straincurve f1′(x) when the amount of strain has been increased from 0% to0.3% with a curve 21 and representing a tensile stress-strain curvef2′(x) when the amount of strain has been decreased from 0.3% with acurve 22. In FIG. 1, the force response behavior of an elasticdeformation resin is indicated by representing a tensile stress-straincurve f1″(x) when the amount of strain has been increased from 0% to0.3% with a curve 31 and representing a tensile stress-strain curvef2″(x) when the amount of strain has been decreased from 0.3% with acurve 32. Furthermore, the curves 31 and 32 are roughly straight lines.

First, the force response behavior of the resin composition according tothe present embodiment is such that force response behavior is exhibitedin which the area surrounded by the following tensile stress-straincurve f1(x) 11, the vertical line at X=0.3 and the x axis (first area)is greater than the area surrounded by the following tensilestress-strain curve f2(x) 12, the vertical line at X=0.3 and the x axis(second area) as shown in FIG. 1. Furthermore, the tensile stress-straincurve f1(x) referred to here is the tensile stress-strain curve when theamount of strain has been increased from 0% to 0.3%. In addition, thetensile stress-strain curve f2(x) is the tensile stress-strain curvewhen the amount of strain has been decreased from 0.3% to the strainamount at tensile stress of 0%. Namely, the tensile stress-strain curvef1(x) and the tensile stress-strain curve f2(x) are different, and theload applied during relaxation so as to decrease the amount of strainfrom 0.3% is smaller than the load applied when pulling so as toincrease the amount of strain from 0% to 0.3%.

In addition, even in the case of a resin composition in which the firstarea and the second area are the same, the first area may be larger thanthe second area due to measurement error and the like. The first areabeing larger than the second area may indicate that the first area issubstantially larger than the second area, excluding such a case ofmeasurement error.

In addition, the cured product exhibits force response behavior suchthat the amount of change in the amount of strain when tensile stress is0 before and after applying tensile stress is 0.05% or less. Namely,when deformation is relaxed after having pulled the cured product to anamount of strain of 0.3%, the cured product returns to roughly the sameshape as the shape prior to applying tensile stress. As shown in FIG. 1,the amount of strain when tensile stress is 0 before and after applyingtensile stress is preferably completely unchanged and returns to theorigin.

A resin composition from which is obtained a cured product that exhibitssuch force response behavior allows the obtaining of a compact in whichthe occurrence of warpage is adequately inhibited even in the case ofhaving been bonded to another member. For example, a printed wiringboard bonded to a semiconductor chip is obtained that is able toadequately inhibit the occurrence of package warpage. In addition, thisresin composition also allows the production of an insulating film inwhich the occurrence of warpage is inhibited even if bonded to a memberof a different material in addition to a printed wiring board bonded toa semiconductor chip.

In addition, since a resin composition from which is obtained a curedproduct as described above allows a compact obtained using the resincomposition per se to deform corresponding to a dimensional changecaused by a change in temperature even if another member is bonded tothe compact, the occurrence of warpage is thought to be adequatelyinhibited.

In addition, the load applied during relaxation when the amount ofstrain is decreased from 0.3% is smaller than the load applied duringpulling so that the amount of strain is increased from 0% to 0.3% aspreviously described. On the basis thereof, when deformation of acompact returns to its original shape, it is thought to return slowly.Accordingly, the compact per se is thought to be able to deform so as toadequately inhibit the occurrence of warpage.

In addition, since the amount of strain when tensile stress is 0 issmall as previously described, it is thought to be able to adequatelyaccommodate additional dimensional changes caused by a change intemperature. On the basis thereof, the resin composition is thought toallow the obtaining of a compact in which the occurrence of warpage isadequately inhibited.

In contrast thereto, first in the case of a plastic deformation resin,as shown in FIG. 1, force response behavior is exhibited in which thearea surrounded by the tensile stress-strain curve f1′(x) 21, thevertical line at X=0.3 and the x axis is greater than the areasurrounded by the tensile stress-strain curve f2′(x) 22, the verticalline at X=0.3 and the x axis in the same manner as the resin compositionaccording to the present embodiment. On the basis thereof, the loadapplied during relaxation when the amount of strain decreases from 0.3%can be understood to be smaller than the load applied when pulling sothat the amount of strain increases from 0% to 0.3%. On the basisthereof, in the case where stress is applied to a compact obtained usinga resin composition, the compact is thought to return slowly when thedeformed compact returns to its original shape after having beendeformed. Furthermore, examples of plastic deformation resins includepolyethylene and polypropylene.

However, as shown in FIG. 1, a plastic deformation resin differs fromthe resin composition according to the present embodiment in that theamount of change in the amount of strain when tensile strain is 0 beforeand after applying tensile stress exceeds 0.5%. Namely, a plasticdeformation resin is thought to not return to its original shape even iftensile strain is released. Consequently, a compact obtained by usingthis resin is thought to not return to its original shape even ifdeformed as a result of the application of stress. On the basis thereof,since deformation of this compact per se is not deformationcorresponding to a dimensional change caused by a change in temperature,it is thought to be unable to adequately inhibit the occurrence ofwarpage. Furthermore, examples of elastic deformation resins includeresin compositions containing epoxy resin and the like, polyimide resinand silicone rubber.

In addition, in the case of an elastic deformation resin, differing fromthe resin composition according to the present embodiment, forceresponse behavior is exhibited in which the area surrounded by thetensile stress-strain curve f1″(x) 31, the vertical line at X=0.3 andthe x axis and the area surrounded by the tensile stress-strain curvef2″(x) 32, the vertical line at X=0.3 and the x axis are roughly equal.As shown in FIG. 1, the amount of change in the amount of strain whentensile stress is 0 before and after the application of tensile stressis 0.05% or less. On the basis thereof, a compact obtained from anelastic deformation resin is a material that deforms linearlycorresponding to the applied stress. On the basis thereof, an effect isthought to be able to be exhibited in which the occurrence of warpage inthe case of being bonded to another member due to deformation of thecompact is adequately inhibited. In addition, in order for such amaterial to inhibit the occurrence of warpage, it is thought to be theresult of enhancing the modulus of elasticity and lowering thecoefficient of thermal expansion as previously described.

On the basis of the above, according to the resin composition accordingto the present embodiment, a compact obtained using this resincomposition is thought to be able to adequately inhibit the occurrenceof warpage even in the case of being bonded to another member. Examplesof such compacts include printed wiring boards having a semiconductorchip bonded thereto, and according to the resin composition according tothe present embodiment, a printed wiring board is obtained that is ableto adequately inhibit the occurrence of package warpage.

In addition, each of the tensile stress-strain curves representing thisforce response behavior is preferably measured under the conditionsindicated below.

First, the curve f1(x) is preferably measured by a measurement method inwhich the amount of strain is increased by pulling at 999 μm/min. Inaddition, the curve f2(x) is preferably measured by a measurement methodin which the amount of strain is reduced by decreasing tensile stress bypulling at 1 μm/min after having held the amount of strain at 0.3% for 1minute. When the force response behavior of a cured product is measuredunder such conditions, since it is easy to determine whether or not aresin composition allows the obtaining of a compact in which theoccurrence of stress is inhibited, a resin composition that allows theobtaining of a compact in which the occurrence of warpage is moreeffectively inhibited is considered to be obtained if the cured productsatisfies the force response behavior described above under thesemeasurement conditions. More specifically, even if the amount of strainis held at 0.3% for 1 minute, the amount of strain when tensile stressis 0 returns to the vicinity of 0% in the case of the resin compositionaccording to the present embodiment. In contrast, in the case of theplastic deformation resin, the amount the cured product does not relaxand return to its original shape is thought to increase as this holdingtime becomes longer.

The following indicates a measurement method as an example of a specificmeasurement method.

First, a cured product of a prescribed shape is molded for use as ameasurement test piece using a resin composition. The shape of the curedproduct is such that it is only required to be compatible with themeasuring instrument. Next, the f1(x) and f2(x) curves of the curedproduct are measured under the conditions described above using atensile strength tester for the measuring instrument. An example of atensile strength tester is a thermomechanical analyzer (TMA).

Next, a second proportion of a change in stress relative to a change inthe amount of strain between a first amount of strain when stress is 0and a second amount of strain resulting from adding 0.1% to the firstamount of strain on curve f2(x) is preferably is as indicated below.Namely, the ratio of the second proportion to a first proportion, whichis the proportion of a change in stress relative to a change in theamount of strain for an amount of strain of 0% to 0.1% on curve f1(x)(second proportion/first proportion), is preferably 0.5 or less and morepreferably 0.1 to 0.5.

This first proportion is thought to be equivalent to the elastic moduluswhen a cured product begins to be formed as a result of pulling. Inaddition, the second proportion is thought to be equivalent to theelastic modulus immediately before deformation of the cured productcompletely returns to its original shape. Based on this relationship,the first proportion is thought to be larger than the second proportion,and the elastic modulus at the start of deformation is thought to becomparatively high. On the basis thereof, although the cured productdeforms easily in the case of gradually applying stress, it is thoughtto tend to be resistant to deformation when stress is appliedinstantaneously. On the basis thereof, deformation that inhibits theoccurrence of warpage is thought to occur easily, and use of the resincomposition described above is thought to allow the obtaining of acompact in which the occurrence of warpage is more effectivelyinhibited.

In addition, the ratio of tensile stress on a stress-strain curvef2(0.15) to tensile stress on a tensile stress-strain curve f1(0.15)when the amount of strain is 0.15% [f2(0.15)/f1(0.15)] is preferablyless than 0.9 and more preferably 0.1 to less than 0.9. In the case ofsuch a ratio, in the case where stress is applied to a compact obtainedusing this resin composition, the compact is thought to exhibitperformance in which deformation of the deformed compact returns slowlywhen returning to its original shape. Accordingly, a resin compositionthat satisfies this ratio is able to more effectively inhibit theoccurrence of warpage.

In addition, a fourth proportion of a change in stress relative to achange in the amount of strain between an amount of strain of 0.2% and0.3% on a tensile stress-strain curve f3(x) when the amount of strain isincreased from 0% to 0.3% by pulling at 100 μm/min is preferably asindicated below. Namely, the ratio of the fourth proportion to a thirdproportion of a change in stress relative to a change in the amount ofstrain between an amount of strain of 0.2% and 0.3% on the curve f1(x)(fourth proportion/third proportion) is preferably 0.8 or less. Althoughthis ratio is preferably as low as possible, in actuality, a value ofabout 0.01 is the limit. Consequently, the lower limit of this ratio is0.01. Namely, the ratio of the fourth proportion to the third proportion(fourth proportion/third proportion) is preferably 0.01 to 0.8. Inaddition, this ratio is preferably as low as possible, and morespecifically, it more preferably 0.01 to 0.6 and even more preferably0.01 to 0.2. As a result, a compact obtained using this resincomposition is subjected to little stress in the case of having beenpulled comparatively slowly even in the case of a change in the amountof strain in which the amount of strain is between 0.2% and 0.3% that isnear the end of a change from 0.2% to 0.3%. On the basis thereof, thiscompact is thought to be able to deform corresponding to a change instress at which warpage occurs. Accordingly, a resin composition thatsatisfies this ratio is able to more effectively inhibit the occurrenceof warpage.

In addition, a ratio of the minimum value of stress when the amount ofstrain has been maintained at 1% (maintained stress) to the maximumvalue of stress when pulled so that the amount of strain is 1% (tensilestress) (maintained stress/tensile stress) is preferably 0.05 to 0.95and more preferably 0.1 to 0.95. On the basis thereof, when a compactobtained from the resin composition is maintained in a deformed state,even if the amount of strain does not change, the loaded stress isthought to gradually decrease. Accordingly, even in the case wheredeformation has occurred in response to a temperature change of thecompact, stress that attempts to return that deformation to its originalshape gradually weakens, and this is thought to make it possible to moreeffectively inhibit the occurrence of warpage. Accordingly, a resincomposition that satisfies this ratio is able to more effectivelyinhibit the occurrence of warpage.

In addition, each of the force response behavior previously describedpreferably satisfies each of the above relationships even if pulling andrelaxation is repeated two or more times. Namely, even if pulling whenthe amount of strain has been increased from 0% to 0.3% and itsrelaxation in the form of relaxing when the amount of strain isdecreased from 0.3% are repeated two or more times, each of the aboverelationships is preferably satisfied. As a result of satisfying thisrelationship, additional dimensional changes caused by a change intemperature were determined to be able to be adequately accommodated.Accordingly, a resin composition that satisfies this relationship isable to more effectively inhibit the occurrence of warpage.

In addition, the resin composition according to the present embodimentpreferably contains the components indicated below. For example, theresin composition is preferably a resin composition that contains epoxyresin, phenolic resin, imide resin, cyanate ester resin or vinyl esterresin.

In addition, examples of the resin composition include those containinga curable compound, a curing agent, a resin other than the curablecompound and an inorganic filler.

The curable compound may be a low molecular weight component in the formof a resin that allows the obtaining of a cured product, or may be aresin that allows the obtaining of a cured product by increasingmolecular weight or forming a network structure as a result of curing.More specifically, although there are no particular limitations thereon,examples of the curable compound include epoxy resin, phenolic resin,imide resin, cyanate ester resin, vinyl ester resin, urea resin, diallylphthalate resin, melanine resin, guanamine resin, unsaturated polyesterresin and melamine-urea co-condensed resin. One type of these may beused alone or two or more types may be used in combination. In addition,among the curable compounds listed above, the curable compound ispreferably an epoxy resin, phenolic resin, imide resin, cyanate esterresin or vinyl ester resin. In this case, a compact is easily obtainedthat has the properties described above.

There are no particular limitations on the epoxy resin provided it is anepoxy resin that is used as a raw material of various types of boardsable to be used in the production of laminated boards and circuitboards. More specifically, examples of epoxy resins include naphthaleneepoxy resin, cresol novolac epoxy resin, bisphenol A epoxy resin,bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxyresin, alkyl phenolic novolac epoxy resin, aralkyl epoxy resin, biphenolepoxy resin, dicyclopentadiene epoxy resin, epoxy compounds ofcondensates of phenols and aromatic aldehydes having a phenolic hydroxylgroup, triglycidyl isocyanurate and alicyclic epoxy resins. One type ofthese may be used alone or two or more types may be used in combination.

There are no particular limitations on the phenolic resin provided it isa phenolic resin that is used as a raw material of various types ofboards able to be used in the production of laminated boards and circuitboards. More specifically, examples of phenolic resins include phenolicnovolac resin, cresol novolac resin, aromatic hydrocarbon-formaldehyderesin-modified phenolic resins, dicyclopentadiene-phenol adduct resins,phenol aralkyl resin, cresol aralkyl resin, naphthol aralkyl resin,biphenyl-modified phenol aralkyl resin, phenol trimethylolmethane resin,tetraphenylol ethane resin, naphthol novolac resin, naphthol-phenolco-condensed novolac resin, naphthol-cresol co-condensed novolac resin,biphenyl-modified phenolic resin and aminotriazine-modified phenolicresin. One type of these may be used alone or two or more types may beused in combination.

There are no particular limitations on the imide resin provided it is animide resin that is used as a raw material of various types of boardsable to be used in the production of laminated boards and circuitboards. More specifically, examples of imide resins includepolyamide-imide resins and polylmaleimide resins. Specific examplesinclude imide resins obtained using phenylmethane maleimide, bisallylnadimide, maleic acid N,N-ethylene bis-imide, maleic acidN,N-hexamethylene bis-imide, maleic acid N,N-metaphenylene bis-imide,maleic acid N,N-paraphenylene bis-imide, maleic acidN,N-4,4-diphenylmethane bis-imide, maleic acid N,N-4,4-diphenyl etherbis-imide, maleic acid N,N-4,4-diphenylsulfone bis-imide, maleic acidN,N-4,4-dicyclohexylmethane bis-imide, maleic acidN,N-α,α-4,4-dimethylenecyclohexane bis-imide, maleic acidN,N-4,4-metaxylylene bis-imide, and maleic acidN,N-4,4-diphenylcyclohexane bis-imide. One type of these may be usedalone or two or more types may be used in combination.

There are no particular limitations on the cyanate ester resin providedit is a cyanate ester resin that is used as a raw material of varioustypes of boards able to be used in the production of laminated boardsand circuit boards. More specifically, examples of cyanate ester resinsinclude cyanate ester resins obtained using bis(4-cyanatophenyl)ethane,2,2-bis(4-cyanatophenyl)propane,2,2-bis(3,5-dimethyl-4-cyanatophenyl)methane,2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane,α,α′-bis(4-cyanatophenyl)-m-diisopropylbenzene and cyanato estercompounds of phenol-addition dicyclopentadiene polymers. One type ofthese may be used alone or two or more types may be used in combination.

There are no particular limitations on the vinyl ester resin provided itis a vinyl ester resin that is used as a raw material of various typesof boards able to be used in the production of laminated boards andcircuit boards. More specifically, examples of vinyl ester resinsinclude resins obtained by reacting an unsaturated monobasic acid suchas acrylic acid or methacrylic acid with a known epoxy resin.

In addition, there are no particular limitations on the curing agentprovided it cures the curable compound, and examples thereof includeknown curing agents. Examples of curing agents include dicyandiamide,phenolic curing agents, acid anhydride-based curing agents,aminotriazine novolac-based curing agents and cyanate resin. Inparticular, in the case where the curable compound is an epoxy resin,phenolic curing agents such as a phenolic curing agent having a novolacbackbone in the form of a novolac-based phenolic curing agent or aphenolic curing agent having a naphthalene backbone in the form of anaphthalene-based phenolic curing agent are used preferably. Inaddition, in the case where the curable compound is a cyanate esterresin, a curing agent of a metal-based reaction catalyst is usedpreferably. In addition, in the case where the curable compound is animide resin, a curing agent (crosslinking agent) such as polyamine isused preferably.

In addition, examples of resins other than the curable compound includelow-Tg resins having a glass transition temperature (Tg) of 100° C. orlower. Examples of these low-Tg resins include resins having a carbonylgroup or siloxane group and epoxy group or phenolic hydroxyl group asfunctional groups in a molecule thereof. Namely, examples of theselow-Tg resins include resins having a carbonyl group and an epoxy group,resins having a carbonyl group and a phenolic hydroxyl group, resinshaving a siloxane group and an epoxy group and resins having a siloxanegroup and a phenolic hydroxyl group, which have a Tg of 100° C. orlower. Furthermore, a siloxane group refers to a group having a siloxanebond (Si—O—Si). In addition, the low-Tg resin may be a resin thatfurther has other functional groups in each of the four types of resinslisted above. In addition, Tg of the low-Tg resin is preferably 100° C.or lower, more preferably 80° C. or lower and even more preferably 70°C. or lower. Here, Tg refers to the value obtained by measuring theresin alone with a differential scanning calorimeter (DSC).

In addition, this low-Tg resin is preferably a resin that has both acarbonyl group and epoxy group as functional groups in a moleculethereof. More specifically, the low-Tg resin preferably has repeatingunits represented by the following formula (I) and the following formula(II) and has an epoxy group. The repeating units represented by thefollowing formula (I) and the following formula (II) can serve as, forexample, the main chain of a molecule that composes the low-Tg resin. Inaddition, the epoxy group may be bound to the main chain, may be boundto a side chain or may be bound to the end of the main chain.

In addition, in the formula (I) and the formula (II), R1 represents H orCH₃. In addition, R2 represents H or an alkyl group.

In addition, in the repeating units represented by the formula (I) andthe formula (II), the ratio of x to y is preferably such that x:y=0:1 to0.35:0.65. On the basis thereof, a repeating unit represented by theformula (I) may not be contained in the low-Tg resin. In the case ofhaving both the repeating units of the formula (I) and the formula (II),there are no particular limitations on the order of these sequences. Inaddition, the repeating unit represented by the formula (II) may containa plurality of different types of repeating units (such as a pluralityof repeating units in which R2 differs). In the case where R2 is analkyl group in the repeating unit represented by the formula (II), thereare no particular limitations on the number of carbon atoms thereof. Thenumber of carbon atoms of the alkyl group can be, for example, 1 to 6.In addition, this alkyl group may be linear or branched. A specificexample of a low-Tg resin having the above configuration is anepoxy-modified acrylic resin (acrylic resin having an epoxy group).

In addition, the low-Tg resin preferably has a siloxane group and aphenolic hydroxyl group. More specifically, the low-Tg resin preferablyhas repeating units represented by the following formula (III) and thefollowing formula (IV) in a molecule thereof. Repeating unitsrepresented by the following formula (III) and the following formula(IV) can serve as the main chain of a molecule that composes the low-Tgresin. In addition, in the case where the low-Tg resin has the repeatingunits represented by the following formula (III) and the followingformula (IV) in the main chain thereof, there are no particularlimitations on the sequence order of these two types of repeating units.

In addition, in the formula (IV), R3 and R4 respectively andindependently represent H or a hydrocarbon group having 1 to 6 carbonatoms. In addition, m represents an integer of 1 or more.

A specific example of such a resin is a siloxane-modified phenolicresin, or in other words, a phenolic resin having a siloxane bond.

The weight average molecular weight (Mw) of the low-Tg resin ispreferably 10,000 to 1,000,000 and more preferably 200,000 to 900,000.If the weight average molecular weight is within these ranges, a prepregor metal-clad laminated board has favorable chemical resistance, and aprepreg having superior moldability is easily molded. Here, weightaverage molecular weight refers to, for example, the value measured aspolystyrene by gel permeation chromatography.

In addition, there are no particular limitations on the organic filler.Examples of inorganic fillers include spherical silica, barium sulfate,silicon oxide powder, crushed silica, burnt talc, barium titanate,titanium oxide, clay, alumina, mica, boehmite, zinc borate, zincstannate and other metal oxides and metal hydrates. Containing theseinorganic fillers in a resin composition makes it possible to enhancedimensional stability of a laminated board.

In addition, the resin composition may also contain components inaddition to those described above. For example, the resin compositionmay contain a curing accelerator. There are no particular limitations onthe curing accelerator. Examples of curing accelerators that can be usedinclude imidazole and derivatives thereof, organic phosphorouscompounds, metal soaps such as zinc octanoate, secondary amines,tertiary amines and quaternary amines. The resin composition may alsocontain a photostabilizer, viscosity adjuster or flame retardant and thelike.

In addition, in the resin composition, the weight ratio between thetotal amount of the curable compound and the curing agent and resinother than the curable compound is preferably, for example, 90:10 to50:50. In addition, in the curable compound and the curing agent theequivalence ratio between an epoxy resin and phenolic curing agent ispreferably, for example, 0.8:1.2 to 1.2:0.8. Moreover, the content ofthe inorganic filler is preferably 80% by weight or less based on thetotal weight of the resin composition.

In addition, the respective mixing ratio of each component whenpreparing the resin composition can be suitably adjusted. For example,each component can be mixed so that the content of the curable compoundis 10% by weight to 40% by weight, the content of resin other than thecurable compound is 5% by weight to 40% by weight, and the content ofinorganic filler is 20% by weight to 80% by weight.

In addition, when producing a prepreg, the resin composition accordingto the present embodiment is used by preparing in the form of a varnishfor the purpose of impregnating a base material for forming the prepreg(fibrous base material). The resin composition according to the presentembodiment can be prepared in the form of a varnish (resin varnish).Namely, the resin varnish according to the present embodiment containsthe resin composition and a solvent. This resin varnish allows theobtaining of a compact that adequately inhibits the occurrence ofwarpage. A prepreg obtained by using this resin varnish can be used toproduce a compact such as a printed wiring board that adequatelyinhibits the occurrence of warpage. In addition, this resin varnish canbe prepared, for example, in the manner described below.

First, each component of the resin composition that can be dissolved inan organic solvent is added to an organic solvent and dissolved therein.At this time, the organic solvent may be heated as necessary.Subsequently, components used as necessary that do not dissolve in theorganic solvent, such as the inorganic filler, are added, and the resincomposition is prepared in the form of a varnish by dispersing to aprescribed dispersed state using a ball mill, bead mill, planetary mixeror roll mill and the like. There are no particular limitations on theorganic solvent used here. Specific examples thereof includeketone-based solvents such as acetone, methyl ethyl ketone orcyclohexanone, aromatic solvents such as toluene or xylene, andnitrogen-containing organic solvents such as dimethylformamide.

An example of a method used to produce a prepreg using the resultingresin varnish consists of impregnating a fibrous base material with theresulting resin varnish followed by drying. Namely, the prepregaccording to the present embodiment is obtained by impregnating afibrous base material with the resin varnish. The resulting prepreg canbe used to produce a compact such as a printed wiring board thatadequately inhibits the occurrence of warpage.

Specific examples of fibrous base materials used when producing theprepreg include glass cloth, aramid cloth, polyester cloth, non-wovenglass fabric, non-woven aramid fabric, non-woven polyester fabric, pulppaper and linter paper. Furthermore, the use of glass cloth allows theobtaining of a laminated board having superior mechanical strength, andglass cloth that has undergone leveling treatment is particularlypreferable. More specifically, leveling treatment can be carried out by,for example, continuously pressing the glass cloth with a press roll ata suitable pressure to compress the yarn until it is flat. Furthermore,a thickness of, for example, 10 μm to 200 μm can be used for thethickness of the fibrous base material.

Impregnation of the fibrous base material with the resin varnish iscarried out by immersion or coating and the like. This impregnation canbe repeated a plurality of times as necessary. In addition, at thistime, the composition and resin content can be adjusted as desired byrepeating impregnation using a plurality of resin varnishes havingdifferent compositions and concentrations.

A semi-hard (B stage) prepreg is obtained by heating the fibrous basematerial impregnated with the resin varnish under desired heatingconditions such as by heating for 3 minutes to 15 minutes at 120° C. to190° C.

A method for fabricating a metal-clad laminated board using a prepregobtained in this manner consists of using a single prepreg or layering aplurality of prepregs, layering a metal foil such as copper foil on boththe upper and lower sides or one side thereof, and laminating this byhot press molding to fabricate a laminate clad with metal foil on bothsides or one side. Namely, the metal-clad laminated board according tothe present embodiment is obtained by laminating a metal foil on theprepreg followed by hot press molding. This metal-clad laminated boardcan be used to produce a printed wiring board that adequately inhibitsthe occurrence of warpage.

By forming a circuit in the surface of the fabricated laminate such asby etching the metal foil, a printed wiring board can be obtainedprovided with a circuit in the form of a conductor pattern on thesurface of the laminate. Namely, the printed wiring board according tothe present embodiment is produced using the prepreg. This printedwiring board is able to adequately inhibit the occurrence of warpageeven when in the form of a package having a semiconductor chip bondedthereto.

Although the present description discloses various aspects of technologyas previously described, the primary technology thereof is summarizedbelow.

In the resin composition according to one aspect of the presentinvention, a cured product obtained by curing this resin compositionfirst exhibits force response behavior such that the area surrounded bythe following tensile stress-strain curve f1(x), the vertical line atX=0.3 and the x axis is greater than the area surrounded by thefollowing tensile stress-strain curve f2(x), the vertical line at X=0.3and the x axis. Furthermore, the tensile stress-strain curve f1(x)described here has the amount of strain plotted on the x axis, tensilestress plotted on the y axis, and is a tensile stress-strain curve whenthe amount of strain by pulling at 999 μm/min is increased from 0% to0.3%. Moreover, the tensile stress-strain curve f2(x) is a tensilestrain-strain curve when the amount of strain is decreased from 0.3% tothe strain amount at tensile stress of 0%. In addition, the curedproduct exhibits force response behavior such that the amount of changein the amount of strain when tensile stress is 0 before and afterapplying tensile stress is 0.05% or less.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact that adequately inhibits theoccurrence of stress even in the case of being bonded to another member.For example, a resin composition can be provided that allows theobtaining of a printed wiring board bonded to a semiconductor chip thatis able to adequately inhibit the occurrence of package warpage. Inaddition, this resin composition can be used to produce an insulatingfilm that inhibits the occurrence of warpage even if a member of adifferent material is bonded thereto in addition to the printed wiringboard bonded to a semiconductor chip.

Since a resin composition from which is obtained a cured product asdescribed above allows a compact obtained using the resin compositionper se to deform corresponding to a dimensional change caused by achange in temperature even if another member is bonded to the compact,the occurrence of warpage is thought to be adequately inhibited. Inaddition, since the amount of change in the amount of strain whentensile stress is 0 is small as previously described, additionaldimensional changes caused by a change in temperature are thought to beable to be adequately accommodated. On the basis thereof, the resincomposition is thought to allow the obtaining of a compact thatadequately inhibits the occurrence of warpage.

In addition, in the resin composition, the cured product is preferablysuch that the ratio of a second proportion on the curve f2(x) to a firstproportion on the curve f1(x) is 0.5 or less. Furthermore, the firstproportion is the proportion of a change in stress relative to a changein the amount of strain at an amount of strain of 0% to 0.1% on thecurve f1(x). In addition, the second proportion is the proportion of achange in stress relative to a change in the amount of strain between afirst amount of strain when stress is 0 and a second amount of strainresulting from adding 0.1% to the first amount of strain on the curvef2(x).

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence of stresshas been more effectively inhibited.

The first proportion is thought to be equivalent to the elastic moduluswhen a cured product begins to be formed as a result of pulling. Inaddition, the second proportion is thought to be equivalent to theelastic modulus immediately before deformation of the cured productcompletely returns to its original shape. Based on this relationship,the first proportion is thought to be larger than the second proportion,and the elastic modulus at the start of deformation is thought to becomparatively high. On the basis thereof, although the cured productdeforms easily in the case of gradually applying stress, it is thoughtto tend to be resistant to deformation when stress is appliedinstantaneously. On the basis thereof, deformation that inhibits theoccurrence of warpage is thought to occur easily, and use of this resincomposition is thought to allow the obtaining of a compact in which theoccurrence of warpage is more effectively inhibited.

In addition, in the resin composition, the cured product is such thatthe ratio of tensile stress on a stress-strain curve f2(0.15) to tensilestress on a tensile stress-strain curve f1(0.15) when the amount ofstrain is 0.15% is preferably less than 0.9.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence ofwarpage is more effectively inhibited.

In addition, in the resin composition, the curve f1(x) is preferablysuch that the amount of strain is increased by pulling at 999 μm/min aspreviously described, and the curve f2(x) is preferably such that theamount of strain is reduced by decreasing tensile stress by pulling at 1μm/min after having held the amount of strain at 0.3% for 1 minute.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence of stressis more effectively inhibited. This means that, when the force responsebehavior of a cured product is measured under such conditions, since itis easy to determine whether or not a resin composition allows theobtaining of a compact in which the occurrence of stress is inhibited, aresin composition that allows the obtaining of a compact in which theoccurrence of warpage is more effectively inhibited is considered to beobtained if the cured product satisfies the force response behaviordescribed above under these measurement conditions.

In addition, in the resin composition, the cured product is such thatthe ratio of the fourth proportion to the third proportion on the curvef1(x) is preferably 0.8 or less. Here, the third proportion is theproportion of a change in stress relative to a change in the amount ofstrain between an amount of strain of 0.2% and 0.3% on the curve f1(x).In addition, the fourth proportion is the proportion of a change instress relative to a change in the amount of strain between an amount ofstrain of 0.2% and 0.3% on a tensile stress-strain curve f3(x) when theamount of strain is increased from 0% to 0.3% by pulling at 100 μm/min.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence ofwarpage is more effectively inhibited.

In addition, in the resin composition, the cured product is such thatthe ratio of the minimum value of stress when the amount of strain hasbeen maintained at 1% to the maximum value of stress when pulled so thatthe amount of strain is 1% is preferably 0.05 to 0.95.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence ofwarpage is more effectively inhibited. On the basis thereof, when acompact obtained from the resin composition is maintained in a deformedstate, even if the amount of strain does not change, the loaded stressis thought to gradually decrease. Accordingly, even in the case wheredeformation has occurred in response to a temperature change of thecompact, stress that attempts to return that deformation to its originalshape gradually weakens, and this is thought to make it possible to moreeffectively inhibit the occurrence of warpage.

In addition, in the resin composition, the stress response behavior ispreferably stress response behavior in which increases and decreases inthe amount of strain are repeated two or more times.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence of stressis more effectively inhibited. On the basis thereof, additionaldimensional changes caused by a change in temperature can be adequatelyaccommodated.

In addition, the resin composition preferably contains at least one typeselected from the group consisting of epoxy resin, phenolic resin, imideresin, cyanate ester resin and vinyl ester resin.

According to this configuration, a resin composition can be providedthat allows the obtaining of a compact in which the occurrence of stressis more effectively inhibited.

In addition, the resin varnish according to another aspect of thepresent invention contains the resin composition and a solvent.

According to this configuration, a resin varnish can be provided thatallows the obtaining of a compact in which the occurrence of stress ismore adequately inhibited. A prepreg obtained using this resin varnishcan be used to produce a compact such as a printed circuit board inwhich the occurrence of warpage is adequately inhibited.

In addition, the prepreg according to another aspect of the presentinvention is obtained by impregnating a fibrous base material with theresin varnish.

According to this configuration, a prepreg can be provided that can beused to produce a compact such as a printed wiring board in which theoccurrence of warpage is adequately inhibited.

In addition, the metal-clad laminated board according to another aspectof the present invention is obtained by laminating a metal foil onto theprepreg followed by hot press molding.

According to this configuration, a metal-clad laminated board can beprovided that can be used to produce a printed wiring board in which theoccurrence of warpage is adequately inhibited.

In addition, the printed wiring board according to another aspect of thepresent invention is produced by using the prepreg.

According to this configuration, a printed wiring board can be providedthat is able to adequately inhibit the occurrence of warpage even whenin the form of a package having a semiconductor chip bonded thereto.

Although the following provides a more detailed explanation of thepresent invention through examples thereof, the scope of the presentinvention is not limited thereto.

EXAMPLES Example 1

A resin composition having the composition indicated below was used.

A resin composition was obtained by blending 48.06 parts by weight ofnaphthalene epoxy resin (HP9500, DIC Corporation), 21.94 parts by weightof novolac-based phenolic curing agent (TD2090, DIC Corporation), 30parts by weight of epoxy-modified acrylic resin (SG-P3, Nagase ChemtexCorporation), 0.05 parts by weight of a curing accelerator in the formof imidazole (2E4MZ: 2-ethyl-4-methylimidazole, SHIKOKU CHEMICALSCORPORATION) and 50 parts by weight of spherical silica (SC2500-GFL,Admatechs Company Limited).

Furthermore, the epoxy-modified acrylic resin (SG-P3, Nagase ChemtexCorporation) is a resin that has repeating units represented by theformula (I) and the formula (II), wherein R1 represents a hydrogen atomand R2 represents a butyl group or ethyl group in formula (II), and hasan epoxy group, in a molecule thereof. In addition, the epoxy-modifiedacrylic resin (SG-P3, Nagase Chemtex Corporation) has a weight averagemolecular weight (Mw) of 850,000, an epoxy value of 0.2 eq/kg and a Tgof 12° C.

Moreover, this resin composition was diluted with a solvent in the formof methyl ethyl ketone (MEK) to obtain a resin composition in the formof a varnish (resin varnish).

A compact measuring 3 mm wide, 20 mm long and 0.06 mm thick wasfabricated using the resulting resin varnish.

The force response behavior of the compact was measured using athermomechanical analyzer (TMA/SS7100, Hitachi High-Tech ScienceCorporation). More specifically, a tensile stress-strain curve f1(x) wasmeasured when the amount of strain was increased from 0% to 0.3% bypulling at 999 μm/min while plotting the amount of strain on the x axisand tensile stress on the y axis. Subsequently, a tensile stress-straincurve f2(x) was measured when the amount of strain was reduced from 0.3%by decreasing tensile stress by pulling at 1 μm/min after having heldthe amount of strain at 0.3% for 1 minute. In addition, separate fromthe above, a tensile stress-strain curve f3(x) was measured when theamount of strain was increased from 0% to 0.3% by pulling at 100 μm/min.

The area surrounded by f1(x) and the x axis was greater than the areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was 0.005%. In addition, tensile stress for f1(0.15) was84.7 mN/mm² and tensile stress for f2(0.15) was 39.1 mN/mm². The ratioof f2(0.15)/f1(0.15) was about 0.46. The ratio of the secondproportion/first proportion was about 0.25. The ratio of the fourthproportion/third proportion was about 0.17. In addition, the ratio ofmaintained stress/tensile stress was about 0.3.

A semiconductor chip was bonded to the board obtained using the resinvarnish, the gap between the board and semiconductor chip was solidifiedwith an underfill material, and the resulting test piece was used toevaluate warpage. Furthermore, the board contained in this test piece isconsidered to be equivalent to a printed wiring board in which only acircuit formed with copper foil and the like is not formed. On the basisthereof, warpage of this test piece was considered to be equivalent towarpage of a package in which a semiconductor chip is bonded to aprinted wiring board.

The amount of warpage of this fabricated test piece at 25° C. wasmeasured by placing the test piece on a smooth surface and measuring themaximum value of the distance between the smooth surface and the lowerend surface of the test piece. As a result, the amount of warpage of thetest piece at 25° C. was 102 μm.

Next, the amount of warpage induced by a temperature change from 25° C.to 260° C. was measured. More specifically, the amount warpage of thetest piece at 260° C. was measured in the same manner as in the case ofmeasuring at 25° C. as described above with the exception of changingthe temperature. The sum of the amount of warpage of the test piece at260° C. and the amount of warpage of the test piece at 25° C. was takento be the amount of warpage caused by a temperature change from 25° C.to 260° C. As a result, the amount of warpage caused by this temperaturechange was 285 μm.

Example 2

Example 2 was carried out in the same manner as Example 1 with theexception of using a resin composition having the composition indicatedbelow.

A resin composition was obtained by blending 38.59 parts by weight ofnaphthalene epoxy resin (HP9500, DIC Corporation), 15.35 parts by weightof novolac-based phenolic curing agent (TD2090, DIC Corporation), 46.06parts by weight of siloxane-modified phenolic resin (GPI-LM, Gun EiChemical Industry Co., Ltd.), 0.05 parts by weight of a curingaccelerator in the form of imidazole (2E4MZ: 2-ethyl-4-methylimidazole,SHIKOKU CHEMICALS CORPORATION) and 50 parts by weight of sphericalsilica (SC2500-GFL, Admatechs Company Limited).

Furthermore, the siloxane-modified phenolic resin (GPI-LM, Gun EiChemical Industry Co., Ltd.) is a resin that has repeating unitsrepresented by the formula (III) and the formula (IV), wherein R3represents a hydrogen atom or hydrocarbon group having 1 to 6 carbonatoms and R4 represents a hydrogen atom or hydrocarbon group having 1 to6 carbon atoms in formula (IV). In addition, the siloxane-modifiedphenolic resin (GPI-LM, Gun Ei Chemical Industry Co., Ltd.) has a weightaverage molecular weight (Mw) of 47,000 and a Tg of 55° C.

Moreover, this resin composition was diluted with a solvent in the formof methyl ethyl ketone (MEK) to obtain a resin composition in the formof a varnish (resin varnish).

The force response behavior of a compact was measured using theresulting resin varnish according to the same method as that of Example1.

The area surrounded by f1(x) and the x axis was greater than the areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was 0.03%. In addition, tensile stress for f1(0.15) was143.6 mN/mm² and tensile stress for f2(0.15) was 37.5 mN/mm². The ratioof f2(0.15)/f1(0.15) was about 0.26. The ratio of the secondproportion/first proportion was about 0.39. The ratio of the fourthproportion/third proportion was about 0.59. In addition, the ratio ofmaintained stress/tensile stress was about 0.93.

A test piece was fabricated using this resin composition according tothe same method as Example 1 followed by measurement of the amount ofwarpage thereof.

The amount of warpage of the fabricated test piece at 25° C. was 106 μM.The amount of warpage caused by a temperature change from 25° C. to 260°C. was 226 μm.

Example 3

Example 3 was carried out in the same manner as Example 1 with theexception of using a resin composition having the composition indicatedbelow.

A resin composition was obtained by blending 30 parts by weight ofepoxy-modified acrylic resin (SG-P3, Nagase Chemtex Corporation), 35parts by weight of imide resin (BMI-2300, Daiwakasei Co., Ltd.), 35parts by weight of imide resin (MANI-M, Maruzen Petrochemical Co.,Ltd.), 0.05 parts by weight of a curing accelerator in the form ofimidazole (2E4MZ: 2-ethyl-4-methylimidazole, SHIKOKU CHEMICALSCORPORATION) and 50 parts by weight of spherical silica (SC2500-GFL,Admatechs Company Limited).

Furthermore, this resin composition was diluted with a solvent in theform of methyl ethyl ketone (MEK) to obtain a resin composition in theform of a varnish (resin varnish).

The force response behavior of a compact was measured using theresulting resin varnish according to the same method as that of Example1.

The area surrounded by f1(x) and the x axis was greater than the areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was 0.01%. In addition, tensile stress for f1(0.15) was400.7 mN/mm² and tensile stress for f2(0.15) was 198.2 mN/mm². The ratioof f2(0.15)/f1(0.15) was about 0.49. The ratio of the secondproportion/first proportion was about 0.29. The ratio of the fourthproportion/third proportion was about 0.62. In addition, the ratio ofmaintained stress/tensile stress was about 0.82.

A test piece was fabricated using this resin composition according tothe same method as Example 1 followed by measurement of the amount ofwarpage thereof.

The amount of warpage of the test piece at 25° C. was 235 μm. The amountof warpage caused by a temperature change from 25° C. to 260° C. was 420μm.

Example 4

Example 4 was carried out in the same manner as Example 1 with theexception of using a resin composition having the composition indicatedbelow.

A resin composition was obtained by blending 49 parts by weight ofnaphthalene epoxy resin (HP9500, DIC Corporation), 30 parts by weight ofepoxy-modified acrylic resin (SG-P3-Mw1, Nagase Chemtex Corporation), 21parts by weight of cyanate ester resin (BADCy, Lonza Japan, Ltd.), 0.02parts by weight of a curing accelerator in the form of zinc octanoate(DIC Corporation), and 150 parts by weight of spherical silica(SC2500-GFL, Admatechs Company Limited).

Furthermore, the epoxy-modified acrylic resin (SG-P3-Mw1, Nagase ChemtexCorporation) is a resin that has repeating units represented by theformula (I) and the formula (II), wherein R1 represents a hydrogen atomand R2 represents a butyl group or ethyl group in formula (II), and hasan epoxy group, in a molecule thereof. In addition, the epoxy-modifiedacrylic resin (SG-P3-Mw1, Nagase Chemtex Corporation) has a weightaverage molecular weight (Mw) of 260,000, an epoxy value of 0.2 eq/kg,and a Tg of 12° C.

Moreover, this resin composition was diluted with a solvent in the formof methyl ethyl ketone (MEK) to obtain a resin composition in the formof a varnish (resin varnish).

The force response behavior of a compact was measured using theresulting resin varnish according to the same method as that of Example1.

The area surrounded by f1(x) and the x axis was greater than the areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was 0.009%. In addition, tensile stress for f1(0.15) was297.1 mN/mm² and tensile stress for f2(0.15) was 150.5 mN/mm². The ratioof f2(0.15)/f1(0.15) was about 0.51. The ratio of the secondproportion/first proportion was about 0.28. The ratio of the fourthproportion/third proportion was about 0.65. In addition, the ratio ofmaintained stress/tensile stress was about 0.87.

A test piece was fabricated using this resin composition according tothe same method as Example 1 followed by measurement of the amount ofwarpage thereof.

The amount of warpage of the test piece at 25° C. was 229 μm. The amountof warpage caused by a temperature change from 25° C. to 260° C. was 417μm.

Comparative Example 1

Comparative Example 1 was carried out in the same manner as Example 1with the exception of using a resin composition having the compositionindicated below.

A resin composition was obtained by blending 48.06 parts by weight ofnaphthalene epoxy resin (HP9500, DIC Corporation), 21.94 parts by weightof novolac-based phenolic curing agent (TD2090, DIC Corporation), 30parts by weight of epoxy-modified acrylic resin (SG-P3-Mw1, NagaseChemtex Corporation), 0.05 parts by weight of a curing accelerator inthe form of imidazole (2E4MZ: 2-ethyl-4-methylimidazole, SHIKOKUCHEMICALS CORPORATION), and 250 parts by weight of spherical silica(SC2500-GFL, Admatechs Company Limited).

Furthermore, the epoxy-modified acrylic resin (SG-P3-Mw1, Nagase ChemtexCorporation) is a resin that has repeating units represented by theformula (I) and the formula (II), wherein R1 represents a hydrogen atomand R2 represents a butyl group or ethyl group in formula (II), and hasan epoxy group, in a molecule thereof. In addition, the epoxy-modifiedacrylic resin (SG-P3-Mw1, Nagase Chemtex Corporation) has a weightaverage molecular weight (Mw) of 260,000, an epoxy value of 0.2 eq/kg,and a Tg of 12° C.

Moreover, this resin composition was diluted with a solvent in the formof methyl ethyl ketone (MEK) to obtain a resin composition in the formof a varnish (resin varnish).

The force response behavior of a compact was measured using theresulting resin varnish according to the same method as that of Example1.

The area surrounded by f1(x) and the x axis was roughly equal to thearea surrounded by f2(x) and the x axis. On the basis thereof, thisresin varnish was determined to have an elastic deformation resin as themain component thereof. In addition, the amount of change in the amountof strain when tensile stress was 0 before and after applying tensilestress was 0.005%. In addition, tensile stress for f1(0.15) was 72.5mN/mm² and tensile stress for f2(0.15) was 68.9 mN/mm². The ratio off2(0.15)/f1(0.15) was about 0.95. The ratio of the secondproportion/first proportion was about 1.0. The ratio of the fourthproportion/third proportion was about 0.93. In addition, the ratio ofmaintained stress/tensile stress was about 1.0.

A test piece was fabricated using this resin composition according tothe same method as Example 1 followed by measurement of the amount ofwarpage thereof.

The amount of warpage of the test piece at 25° C. was 388 μm. The amountof warpage caused by a temperature change from 25° C. to 260° C. was 878μm.

Comparative Example 2

A compact measuring 3 mm wide, 20 mm long and 0.06 mm thick wasfabricated in the same manner as Example 1 using a solution obtained bydissolving a polyamide-imide resin (HR16NN, TOYOBO CO., LTD.) in MEK. Inthe use of this compact, the force response behavior of the compact wasthen measured according to the same method as Example 1.

The area surrounded by f1(x) and the x axis was roughly equal to thearea surrounded by f2(x) and the x axis. On the basis thereof, thepolyamide-imide resin was determined to be an elastic deformation resin.In addition, the amount of change in the amount of strain when tensilestress was 0 before and after applying tensile stress was 0.002%. Inaddition, tensile stress for f1(0.15) was 316.8 mN/mm² and tensilestress for f2(0.15) was 310.2 mN/mm². The ratio of f2(0.15)/f1(0.15) wasabout 0.98. The ratio of the second proportion/first proportion wasabout 1.0. The ratio of the fourth proportion/third proportion was about0.95. In addition, the ratio of maintained stress/tensile stress wasabout 1.0.

The solution as described above was coated onto copper foil and driedfor 5 minutes at 250° C. followed by removing the copper foil and usingthe resulting board to fabricate a test piece having a semiconductorchip bonded thereto. The amount of warpage of this test piece was thenmeasured according to the same method as Example 1.

The amount of warpage of the test piece at 25° C. was 411 μm. The amountof warpage caused by a temperature change from 25° C. to 260° C. was 835μm.

Comparative Example 3

Instead of using a compact obtained by using the resin varnish inExample 1, a film having silicone rubber as the main component thereof(0.05 mm thick silicone sheet, Togawa Rubber Company Limited) was cutout to a width of 3 mm, length of 20 mm and thickness of 0.05 mm. Forceresponse behavior was measured using this cut out film according to thesame method as Example 1.

The area surrounded by f1(x) and the x axis was roughly equal to thearea surrounded by f2(x) and the x axis. On the basis thereof, themeasured film was determined to have an elastic deformation resin as themain component thereof. In addition, the amount of change in the amountof strain when tensile stress was 0 before and after applying tensilestress was 0.001%. In addition, tensile stress for f1 (0.15) was 36.1mN/mm² and tensile stress for f2(0.15) was 34.7 mN/mm². The ratio off2(0.15)/f1(0.15) was about 0.96. The ratio of the secondproportion/first proportion was about 1.0. The ratio of the fourthproportion/third proportion was about 0.96. In addition, the ratio ofmaintained stress/tensile stress was about 1.0.

The film as described above was used as a board to fabricate a testpiece having a semiconductor chip bonded thereto. The amount of warpageof the test piece was then measured according to the same method asExample 1.

The amount of warpage of the test piece at 25° C. was 330 p.m. Theamount of warpage caused by a temperature change from 25° C. to 260° C.was 785 μm.

Comparative Example 4

Comparative Example 4 was carried out in the same manner as Example 1with the exception of using a resin composition having the compositionindicated below.

Instead of using a compact obtained using the resin varnish in Example1, a film having polyethylene as the main component thereof(commercially available product) was cut out to a width of 3 mm, lengthof 20 mm and thickness of 0.05 mm. Force response behavior was measuredusing this cut out film according to the same method as Example 1.

Moreover, this resin composition was diluted with a solvent in the formof methyl ethyl ketone (MEK) to obtain a resin composition in the formof a varnish (resin varnish).

The force response behavior of a compact was measured using theresulting resin varnish according to the same method as Example 1.

The area surrounded by f1(x) and the x axis was greater than areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was 0.10%. In addition, tensile stress for f1(0.15) was110.3 mN/mm² and tensile stress for f2(0.15) was 47.0 mN/mm². The ratioof tensile stress of f2(0.15)/f1(0.15) was about 0.43. The ratio of thesecond proportion/first proportion was about 0.9. The ratio of thefourth proportion/third proportion was about 0.86. In addition, theratio of maintained stress/tensile stress was about 0.6.

A test piece was fabricated using this resin composition according tothe same method as Example 1 followed by measurement of the amount ofwarpage thereof.

Since the test piece deformed considerably at high temperatures,accurate values relating to the amount of warpage were unable to bemeasured.

Comparative Example 5

Instead of using a compact obtained using the resin varnish in Example1, a film having polyethylene naphthalate as the main component thereof(Teonex, Teijin DuPont Films Japan Limited) was cut out to a width of 3mm, length of 20 mm and thickness of 0.05 mm. Force response behaviorwas measured using this cut out film according to the same method asExample 1.

The area surrounded by f1(x) and the x axis was greater than the areasurrounded by f2(x) and the x axis. In addition, the amount of change inthe amount of strain when tensile stress was 0 before and after applyingtensile stress was comparatively large at 0.07%. On the basis thereof,the test film was determined to have a plastic deformation resin as themain component thereof. In addition, tensile stress for f1(0.15) was161.8 mN/mm² and tensile stress for f2(0.15) was 142.3 mN/mm². The ratioof f2(0.15)/f1(0.15) was about 0.88. The ratio of the secondproportion/first proportion was about 0.8. The ratio of the fourthproportion/third proportion was about 0.90. In addition, the ratio ofmaintained stress/tensile stress was about 0.85.

The film as described above was used as a board to fabricate a testpiece having a semiconductor chip bonded thereto. The amount of warpageof the test piece was then measured according to the same method asExample 1.

The amount of warpage of the test piece at 25° C. was 473 μm. The amountof warpage caused by a temperature change from 25° C. to 260° C. was 530μm.

The above results are summarized in the following Table 1.

TABLE 1 Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 1 Ex.2 Ex. 3 Ex. 4 Ex. 5 Resin Naphthalene epoxy resin 48.06 38.59 49 48.06Novolac-based phenolic curing agent 21.94 15.35 21.94 Naphthalene-basedphenolic curing agent Epoxy-modified acrylic resin (Mw: 260,000, 0.2eq/kg) 30 30 Epoxy-modified acrylic resin (Mw: 850,000, 0.2 eq/kg) 30 30Siloxane-modified phenolic resin 46.06 Imide resin 1 35 Imide resin 2 35Cyanate ester resin 21 Polyamide-imide 50 μm 100 Silicone rubber 50 μm100 Polyethylene 50 μm 100 Polyethylene naphthalate 50 μm 100 Curingaccelerator (imidazole) 0.05 0.05 0.05 0.05 Curing accelerator (tinoctanoate) 0.02 Filler Spherical silica 50 50 50 150 250 Total (parts byweight) 150.05 150.05 150.05 250.02 350.05 100 100 100 100 f1(0.15)mN/mm² 84.7 143.6 400.7 297.1 72.5 316.8 36.1 110.3 161.8 f2(0.15)mN/mm² 39.1 37.5 198.2 150.5 68.9 310.2 34.7 47.0 142.3f2(0.15)/f1(0.15) 0.46 0.26 0.49 0.51 0.95 0.98 0.96 0.43 0.88 2ndproportion/1st proportion 0.25 0.39 0.29 0.28 1.00 1.00 1.00 0.90 0.804th proportion/3rd proportion 0.17 0.59 0.62 0.65 0.93 0.95 0.96 0.860.90 Maintained stress/tensile stress 0.3 0.93 0.82 0.87 1.0 1.0 1.0 0.60.85 Warpage (25° C.) μm 102 106 235 229 388 411 330 — 473 Amount ofchange in warpage (25° C.-260° C.) μm 285 226 420 417 878 835 785 — 530

On the basis of these results, in the case of fabricating a packageusing a resin composition that allows the obtaining of a cured productthat exhibits force response behavior in which the first area is greaterthan the second area and the amount of change in the amount of strainwhen tensile stress is 0 before and after applying tensile stress is0.05% or less (Examples 1 to 4), the occurrence of warpage wasdetermined to be able to be adequately inhibited in comparison with thecase of using an elastic deformation resin (Comparative Examples 1 to 3)or in the case of using a plastic deformation resin (ComparativeExamples 4 and 5).

Moreover, the occurrence of warpage in Examples 1 and 2 was extremelylow in comparison with that of Examples 3 and 4, and this is thought tobe due to the low amount of stress generated in Examples 1 and 2 incomparison with Examples 3 and 4.

On the basis of the above, a resin composition that allows the obtainingof a cured product that exhibits force response behavior in which thefirst area is greater than the second area and the amount of change inthe amount of strain when tensile stress is 0 before and after applyingtensile stress is 0.05% or less was determined to be a resin compositionthat allows the obtaining of a compact in which the occurrence ofwarpage is adequately inhibited even in the case of being bonded toanother member.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention hereinafterdefined, they should be construed as being included therein.

1. A resin composition that becomes a cured product that exhibits forceresponse behavior such that an area surrounded by a tensilestress-strain curve f1(x), when an amount of strain is increased from 0%to 0.3% by pulling at 999 μm/min while plotting the amount of strain onthe x axis and tensile stress on the y axis, and also surrounded by thex axis, is greater than an area surrounded by a stress-strain curvef2(x), when the amount of strain is decreased from 0.3%, and alsosurrounded by the x axis, and the amount of change in the amount ofstrain when tensile stress is 0, before and after applying tensilestress, is 0.05% or less.
 2. The resin composition according to claim 1,wherein the cured product exhibits a feature in which the ratio of asecond proportion of a change in stress relative to a change in theamount of strain between a first amount of strain when stress is 0 and asecond amount of strain resulting from adding 0.1% to the first amountof strain on the curve f2(x) to a first proportion of a change in stressrelative to a change in the amount of strain at an amount of strain of0% to 0.1% on the curve f1(x) is 0.5 or less.
 3. The resin compositionaccording to claim 1, wherein the cured product exhibits a feature inwhich the ratio of tensile stress on a stress-strain curve f2(0.15) totensile stress on a tensile stress-strain curve f1(0.15) when the amountof strain is 0.15% is less than 0.9.
 4. The resin composition accordingto claim 1, wherein the curve f2(x) is formed such that the amount ofstrain is reduced by decreasing tensile stress by pulling at 1 μm/minafter having held the amount of strain at 0.3% for 1 minute.
 5. Theresin composition according to claim 1, wherein the cured productexhibits a feature in which the ratio of a fourth proportion of a changein stress relative to a change in the amount of strain between an amountof strain of 0.2% and 0.3% on a tensile stress-strain curve f3(x) whenthe amount of strain is increased from 0% to 0.3% by pulling at 100μm/min while plotting the amount of strain on the x axis and stress onthe y axis to a third proportion of a change in stress relative to achange in the amount of strain between an amount of strain of 0.2% and0.3% on the curve f1(x) is 0.8 or less.
 6. The resin compositionaccording to claim 1, wherein the cured product exhibits a feature inwhich the ratio of the minimum value of stress when the amount of strainhas been maintained at 1% to the maximum value of stress when pulled sothat the amount of strain is 1% is 0.05 to 0.95.
 7. The resincomposition according to claim 1, wherein the stress response behavioris stress response behavior in which increases and decreases in theamount of strain are repeated two or more times.
 8. The resincomposition according to claim 1, which contains at least one typeselected from the group consisting of epoxy resin, phenolic resin, imideresin, cyanate ester resin and vinyl ester resin.
 9. A resin varnishcontaining the resin composition according to claim 1 and a solvent. 10.A prepreg obtained by impregnating a fibrous base material with theresin varnish according to claim
 9. 11. A metal-clad laminated boardobtained by laminating a metal foil onto the prepreg according to claim10 followed by hot press molding.
 12. A printed wiring board produced byusing the prepreg according to claim 10.